Improved circuit-breaking contact assembly for automotive distributors

ABSTRACT

A circuit-breaking lever used in conjunction with ignition arrangements in internal combustion engines. The lever is made of stamped and formed sheet metal which is pivoted at one end about a plastic insulated bushing. The free end of the lever carries a contact which is soldered to the sheet metal member. The contact covers a hole through the sheet metal, and the soldered joint forms a ring-shaped portion about the rim of the hole on one side thereof. The area of the lever on which the contact is located, is formed with a plurality of indentations resulting in a checkered pattern. The hole and the indentations weaken the area to prevent stress-influenced damage to the contact and the area of the lever on which the contact is located.

United States Patent Inventors Oskar Schlossstein Sonthoten;

Leo Steinke, Hegnach, both of Germany 884,199

Dec. 11, 1969 Nov. 9, 197 1 Robert Bosch GmbII Stuttgart, Germany Dec. 13, 1968 Germany Dec. 13, 1968, Germany, No. G 68 11 235.6

Appl. No. Filed Patented Assignee Priorities IMPROVED CIRCUIT-BREAKING CONTACT ASSEMBLY FOR AUTOMOTIVE DISTRIBUTORS 9 Claims, 5 Drawing Figs.

US. Cl 200/19 R,

200/30, 200/166 BH, 29/630 C Int. Cl H0111 19/00 Field of Search 200/ 19-32,

166 BR, 166 C; 29/630 C [56] References Cited UNITED STATES PATENTS 1,780,415 1 1/1930 Baker 200/19 X 2,422,842 6/1947 Molyneux et al. 9 200/166 BH 2,490,020 12/1949 Enzler ...200/ 166 81-1 UX 2,709,207 5/1955 Udale 200/30 2,740,853 4/1956 Hartman, .lr.... 200/30 3,037,096 5/1962 Clevenger 200/19 3,200,226 8/1965 Cooley 29/630 C UX Primary Examiner-J. R. Scott Anomey-Michael S. Striker ABSTRACT: A circuit-breaking lever used in conjunction with ignition arrangements in internal combustion engines. The lever is made of stamped and formed sheet metal which is v pivoted at one end about a plastic insulated bushing. The free end of the lever carries a contact which is soldered to the sheet metal member. The contact covers a hole through the sheet metal, and the soldered joint forms a ring-shaped portion about the rim of the hole on one side thereof. The area of the lever on which the contact is located, is formed with a plurality of indentations resulting in a checkered pattern. The hole and the indentations weaken the area to prevent stress-influenced damage to the contact and the area of the lever on which the contact is located.

" PAIEmEnuuv emn 3.619.521

SHEET 3 UF 3 VE N TORS Oskar S 555 rein Leo Ste fheir A TTORNEY IMPROVED CIRCUIT-BREAKING CONTACT ASSEMBLY FOR AUTOMOTIVE DISTRIBUTORS BACKGROUND OF THE INVENTION The present invention resides in a circuit-breaking lever for ignition arrangements in internal combustion engines. The lever is produced orfabricated from sheet metal and carries a contact which is soldered or braized at its free end.

In circuit-breaking levers of the conventional type and known in the art, stresses arise in the region of the soldered location of the breaker contact on the circuit-breaking lever, after the contact has been soldered or braized in place, and the soldered or braized joint has cooled. These stresses arise from the difierent coefficients of expansion of the different materials used for the sheet metal lever and the contact. When using tungsten contacts, stresses can be compensated or removed only through slow cooling within predetermined limits. With rapid cooling, these stresses lead or produce damaged soldered joints which are defective in operation and result, thereby, in increased fabricating expenditures.

These stresses are removed in a simple manner through the present invention, by weakening the circuit-breaking lever in the region of the soldered or braized joint. These mechanically applied weakenings of the circuit-breaking lever prevent damage or fracture of the soldered joint and contact.

SUMMARY OF THE INVENTION A circuit-breaking device for ignition arrangements in internal combustion engines, in which a sheet metal lever is pivoted through a plastic bushing about a shaft at one end of the lever. The free end of the lever having a mechanically weakened portion; and a contact secured to a predetermined location at said free end of said lever on said weakened portion, said weakened portion preventing stress-influenced damage to said contact and said predetennined location. The weakened portion prevents subsequent damage to the contact and to the lever in cooling at the soldering location as a result of stress influences.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an enlarged elevational view of the circuit-breaking device with a perforated lever at the front end and soldered contact shown partially in sectional form;

FIG. 2 is a plan view of the circuit-breaking lever in FIG. 1;

FIG. 3 is an enlarged elevational view of the circuit-breaking lever with indentations in the region of the soldered location of the contact on the lever, in accordance with the present invention;

FIG. 4 is a plan view of the lever of FIG. 3; and

FIG. 5 is a partial, partly sectional elevational view of the end portion of the lever shown in FIG. 3 drawn to a greatly enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, and in particular to FIG. 1, a circuit breaker, contact breaker or chopper is denoted by the reference numeral 10. This circuit-breaking device consists of a contact-carrying member 11 and a circuit-breaking lever 12. This lever 12 is produced from a stamped and formed sheet metal member 13. A hearing bushing 14 may be of synthetic material such as plastics, for example, and is carried at the back end of the lever 12. A bearing pin or shaft 15 is riveted to the contact carrying member 11, and the interrupting or circuit-breaking lever 12 is slipped onto this shaft or pin 15, with its bearing bushing 14. The arrangement is such that the lever 12 is pivotable about this fixed shaft 15. At the central portion of the circuit-breaking lever 12, is riveted a leaf spring 16. A lug member 17 is, furthermore, riveted together with one end of the spring 16 to the sheet metal portion 13. This lug member 17 rides on the surface of a driven cam, not shown and thereby pivots or rotates the contact-carrying member 11 against the force of the-leaf spring 16, during operation. The leaf spring 16 is held, at one end, by the retaining insulating member 18 on the contact-carrying member 11.

Current is supplied to the circuit breaker through a cable 19 which is electrically in contact with one end of the leaf spring 16. The junction of the cable 19 with the leaf spring 16 is embedded within the plastic insulator member 18. The free end of the cable 19 is joined to a flat plug connector terminal 20. The circuit-breaking lever 12 carries, furthermore, a contact 21 at its frontal free end. This contact 21 is made of tungsten and operates in conjunction with a contact 22 soldered to the contact carrier 11. The tungsten contact 21 is soldered at the frontal end of the sheet metal member 13, through a copper solder or braizing process. The sheet metal member 13 of the circuit-interrupting lever 12 has an opening 24 at the soldered location 23. This opening or hole 24 weakening the sheet metal member 13 has a diameter of 2 mm. The contact 21 has substantially a diameter of 4 mm., and for this reason covers the hole 24 fully on the side at which the contact 21 lies. As a result, the soldered joint includes a ring-shaped rim which extends about the rim 25 of the hole through the sheet metal member 13. Investigations have shown that with this construction in the soldering operation,.unreliable contact closures with the circuit-breaking contacts, are no longer incurred. A further advantage of this solution through the present design resides in the condition that a visible examination of the soldered position is made possible through the hole 24.

The circuit-breaking lever of an ignition interrupter generally designated by the reference numeral 110, is shown in FIGS. 3 and 4. The circuit-breaking lever consists of a stamped and bent or formed sheet metal portion 111. This sheet metal part carries, at one end, a bearing bushing 112 made of synthetic material such as plastics which becomes mounted upon a pivoting shaft or pin, not shown. At the central portion of this circuit-breaking lever, a leaf spring 113 and a lug member 114 are riveted to the sheet metal portion 111. Thus lug member 114 rides upon a cam surface not shown. During operation of the cam which is in contact with the lug 114, the lever 110 becomes angularly displaced against the force applied by the leaf spring 113. A contact 115 is made of tungsten and is carried by the circuit-breaking lever 110 at its frontal free end, and operates in conjunction with a fixed contact. The tungsten contact 115 is soldered or braized to the sheet metal part 111. Since the temperature coefi'tcients of the sheet metal part 111 and the tungsten contact 115 differ from each other, stresses arise after the soldering or braizing'operation in the region of the soldered location 116, upon cooling the latter. These stresses are reduced through the presence of a checkered or ribbed surface 117 on the circuit-breaking lever 110. This checkered surface 117 is at the soldered or braized location 116 and on the side 118 of the sheet metal portion 111. The checkered or ribbed surface 117 consists of indentations 119 which form a waffle pattern weakening the sheet metal part 111. The pattern or indentations may be produced through a stamping member which presses the circuit-breaking lever 110 onto a current-conducting base in the form of an electrode for high-frequency soldering or braizing. Prevailing stresses can, furthermore, be removed by the stamping member, so that the sheet metal part 111 becomes simultaneously evened out through the indentations 117.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in circuit-breaking levers for ignition apparatus in internal combustion engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A circuit-breaking device for ignition arrangements in an internal combustion engine, comprising, in combination, a sheet metal lever pivoted at one end and having an opposite free end having a contact carrying-face and an opposite face, said free end having a mechanical weakened portion; a contact extending over said contact-carrying face at said weakened portion of said lever; and a soldering connection sandwiched between said contact and said contact-carrying face and connecting said contact to said contact-carrying face, said weakened portion comprising at least one indentation extending from one to at least closely adjacent the other face and said at least one indentation being located within the confines of said soldering connection, whereby stresses imparted to said free end of said lever will lead to a deformation of said weakened portion before such stresses damage said soldering connection or the contact.

2. A circuit-breaking device as defined in claim 1, wherein said at least one indentation is constituted by a single opening extending between said faces.

3. The circuit-breaking device as defined in claim 2, wherein said opening has a circular cross section with diameter substantially half of the outer dimension of said contact.

4. The circuit-breaking device as defined in claim 3 wherein said contact has a circular cross section with diameter of 4 5. A circuit-breaking device as defined in claim 2, wherein said soldering connection comprises a ring-shaped soldering joint extending about the rim of said opening.

6. A circuit-breaking device as defined in claim 1, wherein said weakened portion comprises a plurality of indentations arranged in a checkered pattern.

7. A circuit-breaking device as defined in claim 6, wherein said plurality of indentations extend from said opposite face toward, but short of, said contact-carrying face.

8. The circuit-breaking device as defined in claim 1 wherein said contact is of tungsten.

9. The circuit-breaking device as defined in claim I wherein said soldered connection comprises a copper-soldered joint.

# i i ll 

1. A circuit-breaking device for ignition arrangements in an internal combustion engine, comprising, in combination, a sheet metal lever pivoted at one end and having an opposite free end having a contact carrying-face and an opposite face, said free end having a mechanical weakened portion; a contact extending over said contact-carrying face at said weakened portion of said lever; and a soldering connection sandwiched between said contact and said contact-carrying face and connecting said contact to said contact-carrying face, said weakened portion comprising at least one indentation extending from one to at least closely adjacent the other face and said at least one indentation being located within the confines of said soldering connection, whereby stresses imparted to said free end of said lever will lead to a deformation of said weakened portion before such stresses damage said soldering connection or the contact.
 2. A circuit-breaking device as defined in claim 1, wherein said at least one indentation is constituted by a single opening extending between said faces.
 3. The circuit-breaking device as defined in claim 2, wherein said opening has a circular cross section with diameter substantially half of the outer dimension of said contact.
 4. The circuit-breaking device as defined in claim 3 wherein said contact has a circular cross section with diameter of 4 mm.
 5. A circuit-breaking device as defined in claim 2, wherein said soldering connection comprises a ring-shaped soldering joint extending about the rim of said opening.
 6. A circuit-breaking device as defined in claim 1, wherein said weakened portion comprises a pluralitY of indentations arranged in a checkered pattern.
 7. A circuit-breaking device as defined in claim 6, wherein said plurality of indentations extend from said opposite face toward, but short of, said contact-carrying face.
 8. The circuit-breaking device as defined in claim 1 wherein said contact is of tungsten.
 9. The circuit-breaking device as defined in claim 1 wherein said soldered connection comprises a copper-soldered joint. 